Boasting a football-shaped headdress was a sign of dominance in dinosaur social communities, and apparently attracted the ladies, researchers report in a new study, the first to link anatomy with mating choice in dinosaurs. The study's main focus, a dinisaur calledProtoceratops andrewsi flaunted a bony appendage called a fril that it used for sexual displays and to assert social dominance.

"Paleontologists have long suspected that many of the strange features we see in dinosaurs were linked to sexual display and social dominance but this is very hard to show," co-author Dr. David Hone, lecturer in Zoology from Queen Mary University of London's (QMUL) School of Biological and Chemical Sciences, said in a news release. "The growth pattern we see in Protoceratops matches that seen for signaling structures in numerous different living species and forms a coherent pattern from very young animals right through to large adults."

In the latest study, researchers analyzed the remains of 37 Protoceratops collected from a fossil site in the Gobi desert known as the Djadochta Formation and from previously published research. Protoceratops was a relatively small dinosaur – no more than two meters in length from snout to tail tip, about the size of a sheep– and adorned with small horns and that large bony frill that extended from the back of its head to its neck.

After assembling the fossils into groups representing four life stages – hatchling babies, young animals, near-adults, and adults – researchers assessed the change in both length and width of the frill. They found that it grew with age and changed in shape, becoming proportionally wider as the dinosaur got older. This growth pattern, researchers say, it what suggests it was likely used to attract suitable mates and helped them to assert the most dominant position in social interactions.

"Biologists are increasingly realizing that sexual selection is a massively important force in shaping biodiversity both now and in the past," Dr. Rob Knell, Reader in Evolutionary Ecology, added in the university's release. "Not only does sexual selection account for most of the stranger, prettier and more impressive features that we see in the animal kingdom, it also seems to play a part in determining how new species arise, and there is increasing evidence that it also has effects on extinction rates and on the ways by which animals are able to adapt to changing environments."